Obesity and leanness at birth and their relationship to body habitus in later childhood.

Prospectively collected data concerning a large group of children were analyzed to determine whether extremes of body habitus at birth were predictive of obesity and leanness at 4 and 7 years of age. A ratio of weight to height (ratio index) was used to determine relative fatness. Neonates who were extremely lean (0 to 5th percentile) or extremely obese (95th to 100th percentile) showed a tendency to persist, albeit at a decreasing rate, in their original habitus at 4 and 7 years of age. This tendency was slightly more marked in the extremely lean than it was in the extremely obese children at 4 and 7 years of age. Children who were extremely lean or obese at 4 years of age seldom abandon that status by 7 years of age. Similarly, most children at the extremes of body habitus at 7 years of age had already attained that status by 4 years of age. In addition to these postnatal trends, a positive correlation was found between the maternal ratio index and pregnancy weight gain, on the one hand, and the ratio index of the children in the extreme categories at each age, on the other.